fix(sensors): add inlet/outlet types to SensorStage

- Add DataType properties to SensorStage
- Fix MicSensor import issues (remove conflicting TYPE_CHECKING)
- Add numpy to main dependencies for type hints

engine/sensors/__init__.py

@@ -151,6 +151,7 @@ class SensorStage:
     """Pipeline stage wrapper for sensors.
 
     Provides sensor data to the pipeline context.
+    Sensors don't transform data - they inject sensor values into context.
     """
 
     def __init__(self, sensor: Sensor, name: str | None = None):
@@ -159,6 +160,22 @@ class SensorStage:
         self.category = "sensor"
         self.optional = True
 
+    @property
+    def stage_type(self) -> str:
+        return "sensor"
+
+    @property
+    def inlet_types(self) -> set:
+        from engine.pipeline.core import DataType
+
+        return {DataType.ANY}
+
+    @property
+    def outlet_types(self) -> set:
+        from engine.pipeline.core import DataType
+
+        return {DataType.ANY}
+
     @property
     def capabilities(self) -> set[str]:
         return {f"sensor.{self.name}"}

engine/sensors/mic.py

@@ -18,9 +18,9 @@ try:
 
     _HAS_AUDIO = True
 except Exception:
-    _HAS_AUDIO = False
     np = None  # type: ignore
     sd = None  # type: ignore
+    _HAS_AUDIO = False
 
 
 from engine.events import MicLevelEvent
@@ -58,7 +58,7 @@ class MicSensor(Sensor):
 
     def start(self) -> bool:
         """Start the microphone stream."""
-        if not _HAS_AUDIO:
+        if not _HAS_AUDIO or sd is None:
             return False
 
         try:
@@ -84,9 +84,7 @@ class MicSensor(Sensor):
                 pass
             self._stream = None
 
-    def _audio_callback(
-        self, indata: np.ndarray, frames: int, time_info: Any, status: Any
-    ) -> None:
+    def _audio_callback(self, indata, frames, time_info, status) -> None:
         """Process audio data from sounddevice."""
         if not _HAS_AUDIO or np is None:
             return